(CNN) — U.S. Marshals are searching for a New York man who faces criminal charges after claiming partial ownership of Facebook. His family is missing as well.

While Paul Ceglia is being called a fugitive, his attorney says he finds it hard to believe he would just take off.

New York state police and U.S. Marshals are looking for clues around parts of rural Wellsville, New York.

“We don’t know why he fled. You don’t know what’s in somebody’s mind when they decide to take off and become a fugitive,” Charles Salina, U.S. Marshal for the Western District of NY said.

Marshals attempted to serve an arrest warrant to Ceglia on Sunday for tampering with his ankle bracelet. They say they found the device connected to a contraption, but no sign of the 41-year-old man or his family.

“They could be together. The wife could be with the kids at some other location but we don’t know that right now so we’re looking for both Ceglia as a fugitive and we’re looking for the wife and the children as missing persons,” Salina said.

Ceglia faces criminal charges for mail and wire fraud connected to the lawsuit he brought against Facebook CEO Mark Zuckerberg. The suit had been thrown out, but he and his attorneys were appealing that decision.

“I believe it was a violation of his First Amendment right to petition the government,” Ceglia’s attorney Robert Ross Fogg said.

Now that Ceglia is missing, his appeal to restore the lawsuit and another appeal to move the criminal charges to a different court are at risk. His attorneys must show cause why the civil suit shouldn’t be dismissed in the next few days.

“We were actually sitting in a very, very good position before this transpired and that is why I find it most baffling and totally inconsistent with the allegations of absconding,” Fogg said.

Fogg says he’s not sure where Ceglia is, but he doesn’t think people should rule out foul play.

“Everyone has Facebook. Individual people have Facebook. Corporations have Facebook. The courts have Facebook. Many judges and many practitioners have great stock, I mean hundreds of thousands of dollars in stock on Facebook,” Fogg said.

Ceglia’s attorney says they will still move forward with all the litigation including defending him in criminal court, even as the manhunt continues.